Effect of shape of polyhouse and variety in the growth and yield of Chilli under humid tropical climate

摘要

In order to study the effect of shape of polyhouse in growth and yield of chilli, three different shaped naturally ventilated polyhouses (namely gable, quonset and mansard/aerodynamic shapes) having same floor area (150 m2), eave height, ridge heightand roof & side ventilation were designed and constructed in north — south direction at HTR&TU, KAU, Vellanikkara, Thrissur, Kerala. Study was conducted by observing the temperature, CO concentration and relative humidity inside the polyhouses. The temperature inside gable shaped greenhouse was found to be lesser than Quonset and Mansard shaped greenhouses. During peak hours of the day (12 pm to 2.30 pm), temperature inside gable shaped greenhouse was 1.5 to 2°C lesser than other two greenhouses. Relative humidity inside gable shaped greenhouse was found to be lesser during night time and more in peak hours of the day. There was no significant difference in the C02 concentration inside the structures.In all the three polyhouses and open field, six varieties of chilli were cultivated to select high yielding varieties of chilli for humid tropical climate under the polyhouse. Statistical analysis of the yield data revealed that all the varieties of chillies gave maximum yield in gable shaped structure and maximum yield was obtained for seirra variety inside gable shaped greenhouse (4.36 kg) and the minimum yield for Ujwala variety in the open field (0.221kg). It was also found that in all the polyhouses, maximum yield was obtained for the seirra variety and minimum yield for Ujwala variety The yield of sierra, NS 230 and NS 1701 was on par in all the greenhouses. The yield of all other varieties was found to be significantly lesser than the sierra variety. The yield under gable shaped polyhouse was about 12 to 15 times more than that of open field and a benefit - cost ratio of 3.07 could be attained. The study revealed that optimal greenhouse design suitable for Kerala homesteads for cultivating chilli is gable shaped structure oriented in north — south direction and sierra variety is more remunerative.